An Integrated, Modular Simulation System for Education ... - Cal Poly

mode. The aircraft was divergent despite commands to the inceptor to correct theoscillations. After the base drag was included and the initial thrust was set to a constantvalue equal the opposite of the base drag the model demonstrated a damped long periodwith a frequency just slightly higher than the value published for the aircraft.There is no provision to model a stall or limit alpha on the main wing or the tail,so putting a step input with too great a control deflection produces poor results after avery short interval as the alpha limits of the wing are exceeded.PortabilityThe c code for the 6 DOF EOM model was created and debugged using a PC thenported to an IRIX operating system Silicon Graphics Onyx. Since the c code uses onlygeneric math functions only minimal changes were required to the code to compile on theOnyx. The math model itself required no changes. The differences were in the S-functioninterface and the changes were minimal. All of the modeling functions for PhEagle IIwere ported to the SGI to confirm portability. The IO functions were not ported as the ccode is specific to the IO cards located in the PC s.SAD FilesThe aircraft data used in the S-functions are standard aircraft data (SAD) fileswritten in ASCII format, so the input files are portable between the PC s andworkstations. The SAD files contain physical characteristics describing an aircraft alongwith non-dimensional stability derivatives in a standard order. In addition to providinginformation to the simulator, the SAD file can be used to create linearized transferfunctions and a state space model of the aircraft.76